public class Example3_6 {
	public static void main (String args[]){
		double sum = 0, item = 1;
		int i = 1,n=20;
		while(i<=n){
			sum = sum + item;
			i=i+1;
			item = item*(1.0/i);
		}
		System.out.println("sum="+sum);
	}
}